The S&P/NZX50 Index gained 35.79 points, or 0.5 percent, to 6,932.74. Within the index, 31 stocks rose, 16 fell and four were unchanged. Turnover was $189 million.

A2 Milk rose 4.9 percent to $2.58. The shares have risen 19 percent since last Tuesday when the company updated shareholders at its annual meeting in Sydney, with the chief executive saying the board wanted to be clear about its performance. In the four months to October, revenue was at $155.2 million, compared to $79.3 million in the same period of the 2016 financial year

"It's broken into a new trading range, it's really well supported and there's good volume running through," said Peter McIntyre, investment adviser at Craigs Investment Partners. "Their four-monthly update has captured the imaginations of investors and institutions alike, particularly with their growth aspirations - we've seen investors flood into that stock, remembering it wasn't that long ago they were trading around $2."

Tower rose 3.6 percent to 72 cents.

"It's bounced after investors have digested their annual result and the separation of good bank, bad bank - the market thinks that's probably the sensible thing to do, they'd be well-capitalised and their capital ratios have to be in order to meet Reserve Bank requirements," McIntyre said. "Some have bought in today thinking it's a logical solution for Tower which has had problems for a long period of time."

Spark was the worst performer, down 3.2 percent to $3.52. The country's biggest telecommunications company has agreed to buy the remaining half share of fibre construction business Connect 8 from its joint venture partner Vocus Communications for an undisclosed sum.

"They were one of the best performers of yesterday but they've given away a lot of gains today - it's a bit of institutional trimming, because the announcement is more positive than negative," McIntyre said. "It gives them more capability for ongoing fibre expansion, they really want to focus on CBDs of Auckland and Wellington - they obviously see a value proposition there."

NZX dropped 1 percent to $1.00. After market close, the stock market operator said it has settled all outstanding matters connected to the litigation by Ralec and neither party will appeal the decision.

Outside the benchmark index, Scott Technology was unchanged at $2.06 . Investors in the industrial robotics firm have been told its order book remains at a high level, with moves afoot to increase its manufacturing capacity and the number of staff. The Dunedin-based company completed a scheme of arrangement in April which raked in $41 million of new capital after Brazilian meat processor JBS took a 50.1 percent majority stake, some existing shareholders sold down, and others took up their entitlements under the associated rights issue. At balance date, the company had $34 million of cash in the bank and no debt.